Field of the Invention
The present invention relates to a linear motor controlling system which is used for a driving or the like of carts of a conveying apparatus for factory automation (FA) and, more particularly, to a controlling system of a moving-magnet type linear motor.
Description of the Related Art
Generally, in a factory-automated production line for assembling industrial products, a conveying system for conveying parts or the like is used. As such a conveying system, a moving-magnet type linear motor system having a mover provided with a plurality of permanent magnets, coils arranged along a moving path of the mover, and current controllers for supplying currents to the coils has been proposed.
Japanese Patent Application Laid-Open No. H05-30784 proposes a driver controlling apparatus of a vertical type linear motor. According to such a driver controlling apparatus, it has a plurality of armature coils, an exciting current to each armature coil is controlled in accordance with a position detection value of the mover, and only when the position detection value lies within a predetermined threshold value, the armature coil is energized, thereby reducing electric power consumption.
Japanese Patent Application Laid-Open No. 2011-50220 proposes a dispersion-arranged linear motor. According to such a dispersion-arranged linear motor, a current which is supplied to a coil is controlled on the basis of a distance between adjacent stators.
Japanese Patent Application Laid-Open No. H05-191962 proposes a moving-field type linear motor. According to such a linear motor, a lead switch is used for control of an energization to coils on a stator side, thereby supplying a current to only a specific coil. In more detail, according to the moving-field type linear motor, by turning on the lead switch at a point of time when a tip of a permanent magnet of a mover has reached an armature coil, the current is supplied to the coil.